| Message ID | YikSav7Y1iEQv8sq@linutronix.de (mailing list archive) |
|---|---|
| State | Superseded |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | [net,v2] xdp: xdp_mem_allocator can be NULL in trace_mem_connect(). | expand |
On Wed, 9 Mar 2022 21:47:38 +0100 Sebastian Andrzej Siewior <bigeasy@linutronix.de> wrote: > --- a/net/core/xdp.c > +++ b/net/core/xdp.c > @@ -357,7 +357,8 @@ int xdp_rxq_info_reg_mem_model(struct xdp_rxq_info *xdp_rxq, > if (IS_ERR(xdp_alloc)) > return PTR_ERR(xdp_alloc); > > - trace_mem_connect(xdp_alloc, xdp_rxq); > + if (xdp_alloc) Eliminate the check when tracing is disabled: if (trace_mem_connect_enabled() && xdp_alloc) -- Steve > + trace_mem_connect(xdp_alloc, xdp_rxq); > return 0; > } >
Sebastian Andrzej Siewior <bigeasy@linutronix.de> writes: > Since the commit mentioned below __xdp_reg_mem_model() can return a NULL > pointer. This pointer is dereferenced in trace_mem_connect() which leads > to segfault. > > The trace points (mem_connect + mem_disconnect) were put in place to > pair connect/disconnect using the IDs. The ID is only assigned if > __xdp_reg_mem_model() does not return NULL. That connect trace point is > of no use if there is no ID. > > Skip that connect trace point if xdp_alloc is NULL. > > [ Toke Høiland-Jørgensen delivered the reasoning for skipping the trace > point ] > > Fixes: 4a48ef70b93b8 ("xdp: Allow registering memory model without rxq reference") > Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> With Steven's fix: Acked-by: Toke Høiland-Jørgensen <toke@redhat.com>
diff --git a/net/core/xdp.c b/net/core/xdp.c index 7aba355049862..8ebb22eb6497c 100644 --- a/net/core/xdp.c +++ b/net/core/xdp.c @@ -357,7 +357,8 @@ int xdp_rxq_info_reg_mem_model(struct xdp_rxq_info *xdp_rxq, if (IS_ERR(xdp_alloc)) return PTR_ERR(xdp_alloc); - trace_mem_connect(xdp_alloc, xdp_rxq); + if (xdp_alloc) + trace_mem_connect(xdp_alloc, xdp_rxq); return 0; }
Since the commit mentioned below __xdp_reg_mem_model() can return a NULL pointer. This pointer is dereferenced in trace_mem_connect() which leads to segfault. The trace points (mem_connect + mem_disconnect) were put in place to pair connect/disconnect using the IDs. The ID is only assigned if __xdp_reg_mem_model() does not return NULL. That connect trace point is of no use if there is no ID. Skip that connect trace point if xdp_alloc is NULL. [ Toke Høiland-Jørgensen delivered the reasoning for skipping the trace point ] Fixes: 4a48ef70b93b8 ("xdp: Allow registering memory model without rxq reference") Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> --- v1…v2: - Instead letting the trace point deal with a NULL pointer, skip the trace point. net/core/xdp.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)